The present invention relates to the use of a graphics tablet to provide input for a computer system. A prior art graphics tablet might include a platen which contains an x-y grid of wire traces on a pc board. For instance, a graphics tablet model number HP9111A made by Hewlett-Packard Company of Palo Alto, Calif. has 56 traces in the x-direction and 46 traces in the y-direction. Typically in the prior art each trace has required its own trace driving circuitry. This circuitry adds significant cost to the manufacture and design of a graphics tablet.